This investigation will constitute the basis for determining the safety of the administration of female hormones (estrogen) to post-menopausal women with lupus, as the safety of hormonal replacement therapy (HRT) remains controversial. The beneficial effects of HRT for cardiovascular protection and bone density are well established. Lupus patients are at increased risk of osteoporosis and hip fractures from the use of steroids, and at increased risk of heart attacks and cardiovascular disease. If HRT proves not to exacerbate lupus, then postmenopausal women with lupus should not be deprived of this therapy. The effect of HRT (conjugated estrogens and progestins) on disease activity in postmenopausal women with lupus will be determined in a multicenter randomized double-blind placebo-controlled trial. The principal investigator for the national study is Dr. Jill Buyon at the Hospital for Joint Diseases (Cornell University, New York, NY); the coordinating center is Johns Hopkins University (Dr. Michelle Petri); and UAB has been recruited as an additional center to help prompt recruitment. Since the research hypothesis is that HRT does not increase the risk of flares, this study has been designed to detect small differences in the number of flares (the total number of patients to be studied at the national level is 300).